Another interesting group of studies popped out of my AI search of PubMed literature. As a statistician, I see that the articles that says it was ok are old ones and from the literature it seems that different results were obtained according to sample methods. Recent studies indicate that mercury does influence the microbiome and there is an absence of contemporary studies (using modern measurement techniques) on dental amalgams to clarify the matter.

In a survey of 640 human subjects, a subgroup of 356 persons without recent exposure to antibiotics demonstrated that those with a high prevalence of Hg resistance in their intestinal floras were significantly more likely to also have resistance to two or more antibiotics….
Representative mercury-resistant isolates of three selected bacterial families (oral streptococci, members of the family Enterobacteriaceae, and enterococci) were also resistant to one or more antibiotics, including ampicillin, tetracycline, streptomycin, kanamycin, and chloramphenicol.  

Mercury released from dental “silver” fillings provokes an increase in mercury- and antibiotic-resistant bacteria in oral and intestinal floras of primates. 1993

The aim of this review is to point out the health hazards of the uncontrolled global use of implanted mercury-leaking dental amalgam fillings. In spite of the pandemic use of amalgam, most dentists and doctors are still ignorant about the levels of mercury exposure and its health implications. This review discusses the following chronically neglected aspects in clinical practice: The use of materials science in calculating the mercury exposure levels, which may exceed the TLVs by an order of magnitude; Microbial dissolution and methylation of mercury from amalgam by oral and intestinal bacteria; Diagnostic problems and effects of chronic mercury exposure with emphasis on intestinal, cardiovascular, mental and neurologic symptoms and disorders; Diagnostic value of faeces–instead of urine examination–as the main indicator of Hg exposure; Lack of control groups unexposed to Hg (amalgam free) for epidemiologic investigations of health problems; Contribution of dental mercury to environmental pollution. In conclusion, a lack of interdisciplinary research and of a critical approach to established clinical routine appears to be the reason for the failure of the dental profession to protect the patient from Hg exposure when saving the tooth.

Dental mercury–a public health hazard. [1994]

The group exposed to dental amalgam (n = 92) had 13 times more mercury in feces than the group that had never been exposed to amalgam (n = 43) and the group whose amalgam fillings had been removed (n = 56). No significant differences in either mercury resistance or antibiotic resistance in the fecal aerobic gram-negative flora of these subject groups were seen.

Antimicrobial and mercury resistance in aerobic gram-negative bacilli in fecal flora among persons with and without dental amalgam fillings. 1995

The results of this study show that there was no significant difference between children with amalgam fillings and those without such fillings with regard to the prevalence, or the proportion, of Hg-resistant bacteria in their oral microflora.

Prevalence and antibiotic resistance profile of mercury-resistant oral bacteria from children with and without mercury amalgam fillings. 2002

 A significant correlation between the prevalence of mercury resistance and multiple antimicrobial resistance in intestinal bacterial strains was observed.

Resistance of the normal human microflora to mercury and antimicrobials after exposure to mercury from dental amalgam fillings. 1996

According to the conclusions of independent evaluations from different state health agencies, the release of mercury from dental amalgam does not present any non-acceptable risk to the general population.

Resistance of the normal human microflora to mercury and antimicrobials after exposure to mercury from dental amalgam filling 1998

the Cu group (CCu group), the Hg group (CHg group), and the Cu + Hg group (CCH group). …Furthermore, compared to the control group, the abundance of bacteria genera Rikenella, Jeotgailcoccus, and Staphylococcus were significantly decreased, whereas the bacteria genus Corynebacterium was significantly increased in the CCu group. The abundance of bacteria genera of Sporosarcina, Jeotgailcoccus, and Staphylococcus were significantly decreased in the CHg group and CCH group. The bacteria genus Anaeroplasma was significantly increased in the CCH group. The results indicated that high doses of Cu and Hg caused histopathological lesions and changed the diversity of microbiota in the cecum of female mice, which provide a theoretical basis for more accurate assessment of the risk in intestinal diseases caused by Cu and Hg.

High Doses of Copper and Mercury Changed Cecal Microbiota in Female Mice. 2018

“Redundancy analysis showed that arsenic and mercury were significantly associated with Parabacteroides and Oscillospira in the gut. ” 2019

My last review was a thumbs down for a poorly presented probiotic. In this review I want to show what a well presented probiotic looks like. I cam across this one from a demo at my local food co-op and was delighted to read the label. Their direct web-site is here

Let us look at some of the labels on 5 of their products:

The Sweet one!

Why do I say “sweet” — because it has some very rare species to see in any probiotic:

• Lactobacillus Jensenii
• Lactobacillus Fermentum

Origin – Animal, human or environment?

That’s why we use coded strains in advanced gut health probiotic. The strains that we use are 100% human strains, are non-GMO, and do not come from animals.

GenuineHealth site

Likely the same source as NovaProbiotics

While looking for information on these strains, I found this page with many of the same strains listed. this site states:

Each bacterial strain part of our collection was isolated, identified and purified after one-time collection either from meconium, placenta or a healthy human subject. The strains were obtained two decades ago and have been naturally replicating in the laboratory ever since, periodically undergoing numerous tests to assure the bacteria are healthy and maintain their positive characteristics.

NovaProbiotics.com

Nova Probiotics appears to be a Canadian firm based in Quebec.

What do we have for actual published research?

It is always a good win when you see all of the species and their relative amounts listed. The icing on the cake would be research for these specific strains… At the moment, I have not found such — I have emailed Nova Probiotics asking if any studies are available.

Bottom Line

For a probiotic mixture, I would give this one a big thumbs up — for the following reasons:

• All of the probiotics are human sourced
• All of the strains listed
• The amount of each strain is listed
• There appears to have been actual studies, as shown on this page.
• The issue may be one of the studies not being published formally.

A reader ask me to review this probiotic (using my usual pro forma approach).

First impression, this company sells many different products — so it is not specialized in probiotics. For many firms this means that they are private branding a product from a different manufacturer and charging a premium.

Downloading their product sheet, I see a problem:

WHAT — they do not know the difference between a strain and a species?!!??? And they do not state how much of each “strain” (cough cough)

For the non-technical, it is usually as easy as 1-2-3

• Lactobacillus is a genus  (1 name!)
• Lactobacillus acidophilus is a species (2 name)
• Lactobacillus acidophilus NCFM is a strain (3 or more names)

Bottom Line

I would classify this as a random pick from your local grocery shop product. It lacks correct description and almost seems to be targeted to the naive.

Again — nothing known technically wrong with the product — just inaccurate and incomplete descriptions that denies an informed decision.

Another interesting study that popped out of the AI filtering. This is of special interest to SIBO folks that have high hydrogen because ”
Methanogenic archaea reduce hydrogen levels “

Important members that have often been disregarded are the methanogenic archaea. Methanogenic archaea reduce hydrogen levels via the production of methane, thereby stimulating food fermentation by saccharolytic bacteria. On the other hand, colonization by archaea has been suggested to promote a number of gastrointestinal and metabolic diseases such as colorectal cancer, inflammatory bowel disease, and obesity.

The relationship between these determinants and the presence and abundance of archaea was analyzed by logistic and linear regression respectively. Three hundred and sixty-nine out of the 472 children (78.2%) were colonized by M. smithii, and 39 out of the 472 children (8.3%) by M. stadtmanae. The consumption of organic yogurt (odds ratio: 4.25, CI95: 1.51; 11.95) and the consumption of organic milk (odds ratio: 5.58, CI95: 1.83; 17.01) were positively associated with the presence of M. smithii. We subsequently screened raw milk, processed milk, and yogurt samples for methanogens. We identified milk products as possible source for M. smithii, but not M. stadtmanae. 

Gut Colonization by Methanogenic Archaea Is Associated with Organic Dairy Consumption in Children. [2017]

As I continue doing an in depth review of AI selected PubMed articles, I came across a study showing that hyperbaric chambers may actually make antibiotics less efficient and encourage antibiotic resistance. This is of concern because using hyperbaric chambers is popular in some communities based on logic such as: “increased oxygen level will kill off bad bacteria”

The sensitivity of selected bacteria to a range of antibiotics was tested under hyperbaric conditions used in saturation diving. The effect of hyperbaric helium and oxygen (heliox) on antibiotic stability and on induction of beta-lactamase was also determined. Increased resistance to penicillin (up to 23%) was shown by Staphylococcus aureus and to gentamicin (up to 46%) and rifampicin (up to 18%) by Escherichia coli and Salmonella typhimurium at 36 and 71 bar pressure. Exposure to 71 bar heliox did not affect antibiotic activity but increased the production of beta-lactamase in inducible S. aureus and Bacillus subtilis and production of beta-galactosidase in inducible E. coli. Increased resistance to antibiotics in saturation diving conditions can be attributed in some cases to the influence of hyperbaric pressure on induction mechanisms in bacteria. The experimental system devised for this work is suitable for more detailed examination of the influence of hyperbaric stress on antibiotic resistance and of its effect on induction mechanisms in general.

The effect of antibiotics on bacteria under hyperbaric conditions. [1996]

“The gram-negative bacilli generally gave reduced zone diameters in oxyhelium,” [1984]  – reduced zone means less effective.

Studies

In reviewing some studies, we find that it produces symptom relief especially where hypoxia is a factor (CFS/ME, FM, IBD, etc). The ‘Dave Berg’ school of thought ascribes this hypoxia to hypercoagulation in the tissue, often localized.

• “Hyperbaric oxygen therapy (HBOT) provides 100% oxygen under pressure, which increases tissue oxygen levels, relieves hypoxia and alters inflammatory pathways. ” [2014]
• ” Recent evidence that hyperbaric oxygen inhibits the actions of certain cytokines, acts as an immune modulator and may help cognitive dysfunction has resulted in a re-examination of its potential role in rheumatic diseases. A case report of a lupus/scleroderma crossover patient is presented whose cognitive dysfunction improved after hyperbaric oxygen therapy.” [1995]
• “For example, under normal conditions age-related macular degeneration involves oxidative stress and death of the retinal pigment epithelial cells. Hyperbaric oxygen therapy may exacerbate these processes…. Delivery of hyperbaric oxygen therapy may need to be modified or it may even be contraindicated in these cases.  ” [2015]
• Hyperbaric oxygen treatment for Parkinson’s disease with severe depression and anxiety: A case report. [2018]
• Hyperbaric Oxygen Therapy for Alzheimer’s Disease [2018].
• Adjunctive Hyperbaric Oxygen Therapy promotes successful healing in patients with refractory Crohn’s disease.[2016]
• Hyperbaric oxygen therapy for digital ulcers due to Raynaud’s disease. [2018]

Bottom Line

Here we encounter a treatment that appears to have good short term effects (i.e. reducing hypoxia) with the possibility of encouraging the underlying condition by promoting resistance or altering the microbiome in an unfavorable direction.   A 1985 study raises questions about the impact of pressure on the cut microbiome which do appear to have been partially answered by a study this year:

• Gut fermentation seems to promote decompression sickness in humans [1985].
• ” Thus, the result suggest that hyperbaric pressure is an important exogenous factor that strongly modulated the intestinal morphology and microbial ecology, and induced several gastrointestinal ailments during hyperbarism. ” [2013]

We aimed to determine whether the composition of the fecal microbiota changes under hyperbaric conditions. In this study, we collected fecal samples from 6 healthy divers at three points during deep diving training (before, 2.1 MPa, end). The frequency of Clostridium cluster XVIII tended to be increased after compression. The frequencies of Clostridium cluster IV and subcluster XIVa were inversely correlated with that of Bacteroides. The compositional changes in the fecal microbiota exhibited interindividual variability. These findings suggest that hyperbaricconditions affect the fecal microbiota.

Effects of hyperbaric conditions on fecal microbiota. [2019]

Is it good or is it bad? It may depend on an individual circumstance.